Devices and methods for treating vascular malformations

ABSTRACT

A system for treating a vascular malformation has an expandable device and a heating device for heating and shrinking the malformation. The expandable device may have deformable elements which plastically deform in the expanded position. The balloon may be self-expanding, balloon expanded or expanded with an actuating rod. A fluid, such as saline, may be introduced during heating when using RF heating. A sealant may also be introduced into the expandable device to further seal the aneurysm.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to treatment of abnormalities in apatient's vascular system. A specific use of the present inventiondescribed below is for the treatment of cerebral aneurysms although thevarious aspects of the invention described below may also be useful intreating other abnormalities such as arteriovenous malformations (AVM),hypervascular tumors, cavernous carotid fistulas, fibroid tumors, andnon-reversible sterilization via fallopial occlusion.

[0002] Cerebral aneurysms are enlargements of the cerebral vasculaturewhich protrude like a balloon from the wall of a cerebral artery. Thecerebral aneurysm has a neck which leads to the parental vessel and abody or “dome” which can vary in diameter from 1-30 mm.

[0003] The wall of the aneurysm is often weak and can rupture, leadingto hemorrhage. Rupture of the aneurysm can kill the patient or leave thepatient with permanent or transitory mental and physical deficits.

[0004] Aneurysms are often treated to prevent rupture, leading tohemorrhage, or to prevent rebleeding of acutely ruptured aneurysms. Aconventional method of treating aneurysms is to fill the aneurysm withcoils. The coils are introduced into the aneurysm one at a time througha delivery catheter until the aneurysm is filled. The aneurysmeventually becomes a solid mass of coils and thrombus.

[0005] A problem with the conventional method of using coils to fillaneurysms is that the aneurysm becomes a relatively solid mass due tocoils and thrombus contained therein. The mass of coil and thrombusexerts pressure on adjacent areas of the brain which may lead to otherproblems. Another problem with the conventional method is that the coilsmust be delivered one at a time into the aneurysm which increases theprocedure time and risk to the patient. For large aneurysms, up totwenty coils may be required to fill the aneurysm.

[0006] It is an object of the invention to provide improved methods anddevices for treating aneurysms. These and other objects of the inventionwill become evident from the description of the preferred embodimentsdescribed below.

SUMMARY OF THE INVENTION

[0007] In a first aspect of the present invention, a method of treatingan aneurysm is provided. An expandable structure is delivered throughthe vasculature in a collapsed position. Once the expandable structureis at the desired location, such as within a cerebral aneurysm, theexpandable structure is expanded. The structure and advantages of theexpandable structure are described below. The aneurysm wall is alsoreduced in size so that the aneurysm does not need to be completelyfilled in the conventional manner. The expandable shape is sized to besmaller than the aneurysm to permit reducing the size of the aneurysm byat least 30% percent.

[0008] A preferred method of reducing the size of the aneurysm is toheat the aneurysmal wall, preferably to a temperature of at least 60°and preferably 60-80° C., which causes the aneurysmal wall to shrink.The aneurysm may be heated in any suitable manner and preferred methodsare monopolar and bipolar RF, laser, microwave, and simple electricalresistance heating. In a preferred method, electrical energy isdelivered to the expandable device itself to generate heat. A fluid maybe introduced into the aneurysm to prevent clotting during heating andto provide thermal and/or electrical conductance. When using RF heating,for example, the fluid may be saline and more preferably hypertonicsaline. Although it is preferred to heat the aneurysmal wall to reducethe size of the aneurysm, the aneurysm may also be reduced in size bychemical action.

[0009] The expandable structure forms a matrix of filaments in theexpanded condition. The matrix preferably forms a woven or braidedstructure, however the filaments may also be randomly oriented,parallel, or non-intersection filaments. The matrix may be flexiblefilaments, such as platinum ribbon, extending randomly, radially orhelically within an expandable, permeable, mesh-like enclosure. Thematerial may also be an expandable material such as polymer, nitinol,stainless steel, tungsten or tantalum and alloys/composites thereof.

[0010] The expandable device preferably fills a volume of at least 10%of the aneurysm volume, more preferably at least 40% and most preferablyat least 60% of aneurysm volume. The expandable device preferably hasinternal filaments within the volume to quickly form a stable thrombus.An advantage of the expandable device is that a three-dimensionalstructure forms without requiring separate delivery of a cage and coilsas described in International Application WO 99/07293. In anotheraspect, the expandable device has a deforming portion which plasticallydeforms when moving to the expanded position. The deformable portionholds the flexible filaments in the expanded position.

[0011] The aneurysm may be reduced in size until the aneurysmal wallcontacts the expandable structure so that the expandable structuresupports and reinforces the aneurysmal wall. In a particularlyadvantageous embodiment of the invention, the expandable structureitself is used to transmit energy to heat the aneurysmal wall whichcauses the aneurysmal wall to fuse to the expandable structure, therebyreinforcing the aneurysmal wall and preventing migration of theexpandable structure into the parental vessel.

[0012] In another aspect of the invention, the aneurysmal wall may bereduced in size together with the expandable device. In a preferredembodiment, the expandable structure is a soft mesh which easilycollapses when the aneurysmal wall is shrunk.

[0013] Various optional steps and structure may also be provided. Forexample, a sealant may be delivered into the aneurysm to ensure that theaneurysm is isolated from the parental artery. An advantage of thepresent invention is that the sealant is held within a matrix formed bythe expandable device which holds the sealant in the aneurysm.

[0014] The proximal portion of the expandable structure may be insulatedto protect the neck of the aneurysm. The insulation may coat only theflexible filaments so that the structure is still permeable to fluid.Alternatively, the insulation may be impermeable to protect the neckfrom hot fluid slowly expelled into the aneurysm or to isolate theaneurysm entirely from the parental vessel.

[0015] The expandable device may have one or more expandable sections.In an embodiment, the expandable device has two expandable sectionswherein energy is delivered to the dome with one of the sections whilethe second section is insulated to protect the neck.

[0016] The expandable device may have a locking mechanism for lockingthe expandable device in the expanded position. The expandable device isnaturally biased toward the collapsed position so that the operator maypartially deploy the expandable device to determine whether the devicehas the appropriate size. If the device does not have the appropriatesize, the device is collapsed and removed and another device having theappropriate size is introduced. The locking mechanism is then actuatedwhen the user is satisfied with the size of the device.

[0017] In still another aspect of the present invention, a catheter hasa cover which is positioned over the neck of the aneurysm to isolate theaneurysm from the parental vessel. The aneurysm is then reduced in sizeas explained above while the cover isolates the aneurysm. The cover alsoprotects the patient from hemorrhage by isolating the aneurysm from theparental vessel. The cover may be periodically moved to expel heatedfluid into the parental vessel when heating and shrinking the aneurysm.

[0018] In yet another aspect of the present invention, a coil is used tocover the neck of the aneurysm to regulate the flow of hot fluid out ofthe aneurysm and into the parental vessel. The pitch of the coil can bevaried by the operator during deployment to allow faster or slowerleakage of hot fluid out of the aneurysm and into the parent arteryduring heating.

[0019] A catheter is also provided which has a low-impedance coil, suchas flat copper ribbon or other suitable material, disposed in thecatheter tip. Upon infusion of saline through the catheter and passageof RF energy through the coil, the saline is heated and conductselectrical energy to heat the fluid.

[0020] These and other aspects and advantages of the invention willbecome evident from the following description, drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a system for treating a patient's vascular system.

[0022]FIG. 2 shows an expandable device in a collapsed position.

[0023]FIG. 3 is a perspective view of the expandable device with themesh removed.

[0024]FIG. 4 is a cross-sectional view of the expandable device.

[0025]FIG. 5 shows the expandable device in an aneurysm.

[0026]FIG. 6 shows the expandable device detached from the deliverycatheter.

[0027]FIG. 7 shows the expandable device of FIG. 6 with a sealantintroduced into a portion of the expandable device.

[0028]FIG. 8 shows the sealant filling the aneurysm and the expandabledevice.

[0029]FIG. 9 shows the expandable device having a proximal portion whichis relatively impermeable to the sealant so that the sealant is retainedin the aneurysm.

[0030]FIG. 10 shows the expandable device filled with an expandablematerial such as random fibers or a coil.

[0031]FIG. 11 shows another expandable device which is deployed with aballoon in a collapsed position.

[0032]FIG. 12 shows the expandable device of FIG. 11 in an expandedposition.

[0033]FIG. 13 shows the expandable device reduced in size and theexpandable device having a proximal portion which is insulated toprotect the neck of the aneurysm.

[0034]FIG. 14 shows the expandable device of FIG. 11 with simpleresistance heating used to shrink a portion of the aneurysm into contactwith the expandable device.

[0035]FIG. 15 shows the use of simple resistance heating to shrinkanother portion of the aneurysm into contact with the expandable device.

[0036]FIG. 16 shows a heating device.

[0037]FIG. 17 shows a heating device with the tip curved.

[0038]FIG. 18 shows the heating device used with the expandable deviceof FIGS. 11-14.

[0039]FIG. 19 shows the aneurysm shrunk into contact with the expandabledevice.

[0040]FIG. 20 shows the expandable device reduced in size duringshrinking of the aneurysm.

[0041]FIG. 21 shows another expandable device having a locking mechanismfor holding the device in the expanded position.

[0042]FIG. 22 shows the expandable device of FIG. 21 with the device inthe expanded position.

[0043]FIG. 23 shows the device of FIGS. 21 and 22 released from thedelivery catheter.

[0044]FIG. 24 shows a catheter having a cover for isolating an aneurysmfrom the parental vessel.

[0045]FIG. 25 is a cross-section of the catheter of FIG. 21 along lineA-A.

[0046]FIG. 26 shows the catheter of FIG. 21 with the cover having acurved shape.

[0047]FIG. 27 shows the catheter of FIG. 21 isolating an aneurysm.

[0048]FIG. 28 shows the aneurysm reduced in size and a thrombogenicmaterial and sealant introduced into the aneurysm.

[0049]FIG. 29 shows only the thrombogenic material in the aneurysm.

[0050]FIG. 30 shows another expandable device in a collapsed position.

[0051]FIG. 31 shows the expandable device of FIG. 30 in an expandedposition.

[0052]FIG. 32 is an alternative embodiment of the device of FIGS. 30 and31.

[0053]FIG. 33 is another alternative embodiment of the device of FIGS.30 and 31.

[0054]FIG. 34 shows a mesh structure for use with any of the expandabledevices described herein.

[0055]FIG. 35 shows a number of expandable device delivered to theaneurysm.

[0056]FIG. 36 shows the aneurysm of FIG. 35 reduced in size.

[0057]FIG. 37 shows a coil for regulating flow between an aneurysm and aparent vessel.

[0058]FIG. 38 shows the coil of FIG. 37 with the windings spaced closetogether to further impede fluid flow between the aneurysm and theparent vessel.

[0059]FIG. 39 shows another catheter for heating tissue.

[0060]FIG. 40 is a cross-sectional view of the distal end of thecatheter of FIG. 39.

[0061]FIG. 41 shows the tip of the catheter of FIGS. 39 and 40 withholes at the distal end of the tip.

[0062]FIG. 42 shows the tip of the catheter of FIGS. 39 and 40 withholes along the side of the tip.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

[0063] Referring to FIG. 1, a system 2 for introducing an expandabledevice 4 into a cerebral aneurysm is shown. A first catheter 6 extendsthrough a penetration in the femoral artery and up to the carotidartery. A second catheter 8 is advanced through the first catheter 6 andinto the cerebral vasculature to the site of the aneurysm or otherabnormality. A delivery catheter 10 is then advanced through the secondcatheter 8. The catheter 10 delivers an expandable device 4 whichpartially fills the aneurysm as will be described below. The system 2also has an energy supply 12 for heating the aneurysm to shrink theaneurysm as will be described below.

[0064] After the expandable device 4 has been delivered to the aneurysmand expanded, the aneurysm is reduced in size as shown in FIG. 6. Theaneurysm may be shrunk partially toward the expandable device 4, intoengagement with the expandable device 4, or may even be shrunk until theexpandable device 4 is also reduced in size. An advantage of shrinkingthe aneurysm is that the aneurysm does not need to be completely filledwith coils in the conventional manner. The conventional method offilling the aneurysm with coils creates a relatively solid mass in theaneurysm which can press against adjacent structures leading to furtherproblems. The expandable device 4 is removably mounted to the end of ashaft 5 in the manner described below so that the expandable device 4may be released in the aneurysm. The expandable device may be releasedwith a mechanical mechanism, a thermoadhesive bond, or anelectrolytically or chemically severable bond.

[0065] The aneurysm may be shrunk in any suitable manner and a preferredmethod is to heat the aneurysmal wall. Shrinking of the aneurysm mayalso be accomplished through chemical action. The aneurysmal wall ispreferably heated to a temperature of 60-80° C. and preferably at least70° C. Depending upon the size of the aneurysm, the aneurysmal wall ispreferably heated for at least 10 seconds and generally between 10seconds and 5 minutes.

[0066] In the preferred system of FIG. 1, the energy supply 12 suppliesRF energy to heat and shrink the aneurysm. The expandable device 4 ispreferably configured as a mono-polar RF electrode 14 and the energysupply 12 is preferably an RF generator. A suitable second electrode(not shown) is placed in contact with the patients skin in theconventional manner. The aneurysm may, of course, be heated with theenergy supply being a hot fluid, laser, microwave, bi-polar RF or aresistance heating device without departing from the scope of theinvention.

[0067] Referring to FIGS. 1 and 4, the catheter 8 has a lumen 16 coupledto a source of fluid 18 which is preferably a conductive fluid such assaline and more preferably hypertonic saline. The lumen 16 may also becoupled to a source of sealant 20 which may be used to seal the aneurysmas described below. The sealant may be any suitable sealant such ascyanoacrylates, ethylene vinyl-alcohol, cellulose acetate polymers,fibrin glues and other liquid-type tissue sealants. The sealants mayalso be bioperodable and/or bio-absorbable. The lumen 16 is also coupledto a vacuum source 22 for suctioning fluids and reducing the size of theaneurysm. A source of contrast 24 is also provided for visualization ofthe aneurysm, vasculature and device positions. A valve 26 couples thelumen 16 to the various sources 18, 20, 22, 24. The delivery catheter 10also has a lumen 28 which may be coupled to the sources 18, 20, 22, 24and discussion of use of the lumen 16 is equally applicable for thelumen 28.

[0068] Referring to FIGS. 2, 3 and 5, the expandable device 4 has firstand second expanding sections 30, 32. Although it is preferred toprovide both the first and second expanding sections 30, 32, theexpandable device 4 may include only one expanding section or three ormore expanding sections without departing from the scope of theinvention. The first section 30 acts as the electrode 14 to deliver RFenergy from the energy source 12 to the aneurysm. The second section 32is insulated and does not transmit energy to the aneurysm so that theneck of the aneurysm is protected. The second section 32 is preferablycoated with PTFE, polyamide, FED, or PFA to prevent RF energytransmission. Protecting the neck of the aneurysm also protectsperipheral vessels adjacent the neck of the aneurysm.

[0069] The second expandable section 32 may be permeable to fluid sothat heated fluid in the aneurysm may be slowly expelled into theparental vessel to dissipate heat. The second section 32 may also have afluid impermeable portion 36 adjacent the neck to further protect theneck of the aneurysm as shown in FIG. 9. The fluid impermeable portion36 is preferably a flexible sheath 38 having a ring or annular shape.The ring shape may interrupted at a radially inner portion 39 so thatheated fluid may still be slowly expelled into the parental vessel.Alternatively, the sheath 38 may completely isolate the aneurysm fromthe parental vessel.

[0070] The first and second expandable sections 30, 32 have a number offlexible filaments 40 which move from the collapsed position of FIG. 2to the expanded position of FIG. 5. The flexible filaments 40 arepreferably woven or braided to form a substantially closed-form meshstructure 42 in the expanded position. The filaments 40 and mesh 42 havethe characteristics described below and are graphically depicted in thedrawings for clarity. A preferred mesh structure 42 is also describedwith reference to FIG. 34 below.

[0071] Referring again to FIGS. 2 and 3, the filaments 40 are positionedover deformable elements 48 which hold the flexible filaments 40 in theexpanded position. Referring to FIG. 3, the deformable elements 48 havecolumns 50 extending between collars 52, 53 at the ends. The deformableelements 48 are formed from tubes which have four cut-out sections 54 toform the columns 50. The collars 52 are then attached to the ends of thetube. The columns 50 are bent outward slightly so that they will buckleoutwardly when compressed. As will be described in further detail below,the deformable elements 48 are plastically deformed when moving to theexpanded position to hold the filaments 40 in the expanded position. Thecolumns 50 may also be designed with curved or sinusoidal shapedsections to improve flexibility.

[0072] Referring to FIG. 4, the proximal and distal collars 52 arethreaded to engage a threaded tip 58 of a guidewire 60 for manipulatingthe expandable device 4. Intermediate collars 62 provide onlythroughholes to hold and guide the expandable device 4 on the guidewire60. When expanding the device 4, the guidewire 60 is pulled until thedevice 4 is trapped between the delivery catheter 10 and the threadedtip 58. The guidewire 60 is then rotated to engage the tip 58 with thedistal threaded collar 52. When the tip 58 is threaded into engagementwith the distal collar 52, the guidewire 60 can be pulled to expand thedevice. When the device 4 is partially expanded, the deformable elements48 may still be within their elastic range so that the expandable device4 will recover the collapsed position when tension is released on theguidewire 60. The operator may then check to see if the device 4 has theappropriate size and shape for the aneurysm before fully deploying thedevice. If the operator determines that the device 4 is too small or toolarge, the device 4 is collapsed and removed and another expandabledevice of appropriate size advanced to the aneurysm.

[0073] When the operator is ready to deploy the device 4, the operatorpulls the guidewire 60 so that the deformable elements 48 undergoplastic deformation and move to the expanded position. Even if thedevice 4 is moved to the expanded position, the operator may stillretrieve the device by engaging the proximal collar 53 with the threadedtip 58 and withdrawing the device into the second catheter 8.

[0074] After the expandable device 4 has been moved to the expandedposition, the aneurysm is then preferably reduced in size. In apreferred method, RF energy is delivered to the first expandable section30 through the guidewire 60 and a conductive fluid, preferablyhypertonic saline, is injected into the aneurysm through the lumen 16 orlumen 28. FIG. 6 shows the aneurysm reduced in size until the aneurysmengages the first section 30. The threaded tip 58 is then disengagedfrom the device 4 leaving the device 4 in the shrunken aneurysm.

[0075] As an optional step, the sealant 64 from the source of sealant 20may also be introduced into the entire aneurysm (FIG. 8) or into justthe second section 32 (FIG. 7) to seal the aneurysm. An advantage of thepresent invention over conventional methods is that the sealant 64 iscontained within the closed-form mesh structure 42 to prevent escape ofthe sealant 64 into the parental vessel. Referring to FIG. 9, a proximalportion 66 may be impermeable to further isolate the aneurysm from theparental vessel. A small amount of the sealant 64 may also be deliveredto completely isolate the aneurysm if necessary as shown at dotted-line68. The method of the present invention described above may, of course,be practiced with any suitable structure other than the structure ofFIGS. 1-9 without departing from the scope of the invention.

[0076] Referring to FIGS. 11-15, another delivery catheter 70 is shownfor use with the system of FIG. 1. The delivery catheter 70 is deliveredthrough the first and second catheters described above. The catheterdelivers an expandable device 4A to the aneurysm through the secondcatheter 8 (see FIG. 1).

[0077] The delivery catheter 70 has an expandable member 72, preferablya balloon 74, for deploying the expandable device 4A. The device 4A isconfigured to retain the expanded position of FIG. 12 after the balloon74 has been deflated. The delivery catheter 70 has an inflation lumen 72coupled to a source of inflation fluid 74 for inflating the balloon(FIG. 1).

[0078] The expandable device 4A is preferably made of a number offlexible filaments 76. The filaments 76 are preferably woven or braidedbut may also be a number of non-woven filaments. The filaments 76 may beany suitable material and a preferred material is platinum alloy (92%platinum, 8% tungsten) wire having a thickness of 0.005-0.003 inch.

[0079] The expandable device 4A may take any shape and may have a numberof predetermined shapes which can be selected depending upon the shapeof the aneurysm and the nature of the patient's vasculature. Referringto FIG. 12, the expandable device 4A has a simple spherical shape.Although the expandable device 4A is shown as spherical, the expandabledevice 4A preferably has a width to height ratio of more than 1.1, morepreferably at least 1.2 and most preferably at least 1.8. The width andheight are defined relative to the aneurysm (FIG. 12) and/or relative toa longitudinal axis 76 of the expandable device 4A. The preferreddimensions provide a relatively large width so that the expandabledevice 4A cannot escape through the neck of the aneurysm afterexpansion. The height of the expandable device 4A provides clearance forshrinking the aneurysmal toward the expandable device. The width toheight ratios are preferred dimensions for all of the embodimentsdescribed herein.

[0080] Once the expandable device 4A has been delivered to the aneurysm,the aneurysm is preferably reduced in size in any manner describedherein. A method of reducing the size of the aneurysm is to deliverenergy to the expandable device 4A from the energy source 12. The energymay be delivered to the aneurysm by delivering RF energy to theexpandable device 4A with one or more wires 80 passing through thesecond catheter 8. During RF delivery, the second catheter 8 may be usedto deliver fluid, such as hypertonic saline, to the aneurysm.

[0081] Referring to FIGS. 14 and 15, simple resistance heating may alsobe used by moving the wires 80 into contact with the expandable device4A to conduct electricity therebetween as shown in FIG. 14. An advantageof the system is that different portions of the aneurysm can be heatedto shrink the aneurysm as shown in FIGS. 14 and 15.

[0082] The expandable device 4A may be insulated at a proximal portion82 so that energy is delivered to the aneurysm dome rather than towardthe neck and parental artery. The flexible filaments 76 may be coatedwith any suitable insulation, such as paraline, and may be applied byspraying, dipping or etching. The expandable device 4A may also have theflexible sheath 78 over the insulated region to further shield the neckof the aneurysm.

[0083] Referring to FIG. 16, a heating device 84 is shown which may beused to heat and shrink the aneurysm. The heating device 84 is advancedinto the aneurysm to heat fluid in the aneurysm thereby heating andshrinking the aneurysmal wall. Two insulated wires 86, 88 are wrappedaround a core wire 90 and covered with a sheath 92 along the proximalportion. The sheath 92 forms a lumen 94 therethough which may be coupledto the various sources 18, 20, 22, 24 described above with connector 96.The distal end of the wires 86, 88 form proximal and distal electrodes98, 100 for bipolar RF heating. The core wire 90 is attached to thedistal electrode 100.

[0084] An actuator 102 is manipulated to change the distance between theelectrodes 98, 100 and to bend the tip in the manner shown in FIG. 17.The actuator 102 is coupled to the core wire 90. The device may beconfigured so that the electrodes 98, 100 move toward another when theactuator 102 is manipulated, or the device may be configured so that thetip curves as shown in FIG. 17. The tip may be curved to navigatetortuous vessels and may be curved during heating. In use, the distalend of the device 84 is introduced into the aneurysm and the actuator102 is manipulated to curve the distal end. RF energy is then deliveredand a fluid, such as hypertonic saline, is delivered through the secondcatheter 8 or through the lumen 94.

[0085] Referring to FIGS. 18 and 19, the aneurysm may be shrunk intocontact with the expandable device so that the expandable device 4Areinforces the aneurysmal wall to prevent rupture. The aneurysmal wallmay also be shrunk further so that the expandable device 4A itselfshrinks as shown in FIG. 20. After the aneurysm has been reduced insize, the sealant 64 may also be delivered to further seal the aneurysm.

[0086] Referring to FIGS. 1 and 21-24, another delivery catheter 110 fortreating an aneurysm with the system 2 of FIG. 1 is shown. The catheter110 is advanced to the carotid artery and the second catheter 8 isadvanced through the first catheter 6 to the aneurysm. The deliverycatheter 110 extends through the second catheter 8 to deliver anexpandable device 4B to the aneurysm. The delivery catheter 110 has alumen 112 which may be coupled to one or more of the various sources 18,20, 22, 24. The expandable device 4B is coupled to the energy source 12for heating and shrinking the aneurysm as will be described below.

[0087] The expandable device 4B is movable from the collapsed positionof FIG. 21 to the expanded position of FIG. 22. Flexible filaments 114preferably form a woven or braided mesh structure 116 extending betweenfirst and second hubs 118, 120. A central post 122 extends from thesecond hub 120 and has a locking mechanism 124 which engages the firsthub 118 to hold the expandable device 4B in the locked position. Anactuator 126, which is preferably a tapered rod 128, has a threadedconnection 130 with the central post 122. The actuator 126 is pulled tomove the locking mechanism 124 into engagement with the second hub 120.The locking mechanism 124 has spring elements 126 which are naturallybiased to the position of FIG. 23. The spring elements 126 are angledproximally so that they are displaced inwardly by the hub 118 when thepost 122 and spring elements 126 pass through the hub 118. After thespring elements 126 have passed through the hub 118 they assume theirunbiased shape thereby locking the device 4B in the expanded position.The locking mechanism 124 may be any suitable locking mechanism.

[0088] The flexible filaments 114 preferably bias the device 4B towardthe collapsed position so that the operator may partially expand thedevice to determine whether the device has the appropriate size. If thedevice is not the appropriate size, the device can be collapsed andwithdrawn through the second catheter 8. After the expandable device 4Bhas been expanded, the aneurysmal wall may then be shrunk in any mannerdescribed herein. In the preferred embodiment of FIG. 21, the expandabledevice is a monopolar RF electrode with the energy source being an RFgenerator coupled to the actuator 126. The expandable device 4B may beinsulated along a proximal portion 116 to protect the neck, parentalvessel and adjacent vessels as mentioned above. After the aneurysmalwall has been reduced in size, the sealant 64 (FIG. 8) may be introducedto isolate the aneurysm from the parental vessel.

[0089] In another aspect of the present invention, the expandabledevices 4, 4A, and 4B may be filled with an expandable thrombogenicmaterial 130. Referring to FIG. 10, the expandable device 4 is filledwith the compressible, thrombogenic material 130 which may be randomlyoriented fibers 132 or coils 134. When the expandable device 4 isexpanded, the material 130 expands to occupy the interior volume of thewoven or braided mesh structure 42. The material 130 may be used withany of the expandable devices described herein without departing fromthe scope of the invention. When the material 130 includes filaments136, the filaments 136 may be helically, radially or randomly orientedwithin the interior volume of the mesh or braided structure 42.

[0090] Referring to FIGS. 1 and 24-27, another catheter 140 for treatingan aneurysm with the system of FIG. 1 is shown. The first catheter 6 isintroduced through the femoral artery and advanced to the carotidartery. The second catheter 8 is advanced through the first catheter 6to the aneurysm. The delivery catheter 140 is passed through the secondcatheter 8 to the aneurysm to treat the aneurysm.

[0091] The delivery catheter 140 has a lumen 142 which is coupled to thesources of fluid, contrast, sealant and vacuum 18, 20, 22, 24. Thedistal end of the catheter 140 has a cover 144 which is positioned overthe neck of the aneurysm as shown in FIG. 27. The cover 144 providestemporary isolation of the aneurysm from the parental vessel. The cover144 is preferably a disc of relatively soft material such as silicone.The cover 144 is preferably configured to cover an area of about 0.8 mm²to 75 mm² and is relatively thin so that the cover 144 does not impedeflow through the parental vessel and so that the cover 144 can distortto a small profile when passing through the second catheter 8. The cover144 is also preferably impermeable so that the cover 144 can isolate theaneurysm from the parental vessel.

[0092] The catheter 140 has an electrode 146 which is coupled to theenergy source 12 with a wire 148 extending through the catheter 140. Theelectrode 146 may be configured as a monopolar RF electrode for deliveryof RF energy with a second electrode (not shown) in contact with thepatient's skin. Alternatively, a second electrode 150 may be passedthrough the lumen 142 to provide monopolar or bipolar RF with the firstand/or second electrodes 146, 150. Shrinking of the aneurysm may, ofcourse, be accomplished with any of the methods described above. Forexample, the heating device 84 (FIG. 16) may be advanced through thelumen 142 to heat and shrink the aneurysm.

[0093] Use of the delivery catheter 140 is now described, the deliverycatheter 140 is advanced through the second catheter 8 to the aneurysm.The cover 144 is positioned over the neck of the aneurysm and theaneurysm is heated to shrink the aneurysm. When using RF heating, fluidsuch as hypertonic saline may be infused into the aneurysm through thecatheter 140 or second catheter 8 (FIG. 1). The cover 144 may beflexible enough to deflect and permit hot fluid to be slowly expelledinto the parental vessel. Alternatively, the cover 144 may beperiodically moved away from the neck so that hot fluid in the aneurysmmay be slowly expelled into the parental vessel. The aneurysm may bereduced to an acceptable size or partially shrunk and filled with thethrombogenic material 130 and sealant (FIG. 28) or just the material 130(FIG. 29). Although the delivery catheter 140, and particularly thecover 144, have been described in connection with RF delivery, the cover144 may be incorporated into any of the other catheters described hereinor any other catheter without departing from the scope of the invention.

[0094] Referring to FIGS. 30-34, another expandable device 160 is shownfor use with the system of FIG. 1. The expandable device 160 is advancedthrough the second catheter 8 with a delivery catheter 162. Theexpandable device has a mesh 166 which covers a spring 160 made of ashape memory material. The expandable device 160 is in the collapsedshape of FIG. 30 when advanced through the second catheter 8. After theexpandable device 160 is within the aneurysm, a wire 161 or other devicecan be advanced to contact the device 160 to heat the device and theaneurysm. Upon heating, the coil collapses to the shape of FIG. 31 tomove the mesh 166 to the expanded condition. Heating of the coil may beundertaken in any manner described herein. An advantage of the device160 is that the device may be heated together with the aneurysm todeploy the device 160 while shrinking the aneurysm. Referring to FIG.32, another device 160A is shown which is substantially the same as thedevice 160 except that spring 160A expands in the middle. FIG. 33 showsstill another device 160B which has a smaller diameter in the middle toimpede fluid flow through the spring 160.

[0095] Referring to FIG. 34, another mesh 42A is shown. The mesh 42A maybe used with any of the expandable devices described herein and themechanism for expanding and holding the mesh 42A has been omitted fromFIG. 34 for clarity. Any of the actuating and delivery methods anddevices described above or any other suitable device may be used withthe mesh 42A. The mesh 42A preferably has 10-50 filaments, morepreferably 20-50 filaments, extending between first and second ends 150,152. The filaments 148 are preferably platinum alloy (such as 92%platinum, 8% tungsten). The filaments 148 preferably form a tube in thecollapsed position which has a diameter of no more than 0.020 inch butexpands to a diameter of at least 0.200 inch at a central portion 154.

[0096] The devices described herein are preferably delivered to theaneurysm to occupy the remaining volume of the aneurysm after shrinkingthe aneurysm. Referring to FIGS. 35 and 36, a number of devices 170 maybe delivered to the aneurysm with one of the devices 171 being used toheat and shrink the aneurysm. The devices 170 may be partially orcompletely insulated in the manner described above to protect the neckwhile heating and shrinking is accomplished with the device 171. Thedevices 170 and 171 are shown spaced apart for clarity but, of course,will be closely packed together when filling the aneurysm. The devices170 and 171 may be any of the expandable devices described herein or anyother suitable device without departing from the scope of the invention.

[0097] Referring to FIG. 37, another system for reducing the size of ananeurysm is shown. A coil 172 is used to regulate flow of fluid betweenthe aneurysm and the parent vessel. The coil 172 is particularly usefulfor holding heated fluid in the aneurysm to heat and shrink theaneurysm. The heating device 84 of FIGS. 16 and 17, or any othersuitable device for heating the aneurysm, is introduced into theaneurysm to heat and shrink the aneurysm. The coil 172 is manipulated bypulling or pushing the coil to retract or deploy the coil 172 from thecatheter 8 (see FIG. 1). The pitch of the coil 172 can be varied bypulling or pushing the catheter 8 relative to the coil 172. The windingsof the coil 172 may be close together so that the coil 172 substantiallyimpedes flow between the aneurysm and the parent vessel (FIG. 38) or maybe spaced-apart to permit slow leakage of fluid into the parent vessel.The coil 172 may be made of any suitable material and is preferably ashape-memory alloy such as nitinol.

[0098] Referring to FIGS. 39 and 40, another catheter 180 for heatingand shrinking an aneurysm is shown. The catheter 180 is preferably lessthan 5 Fr, more preferably 2-4 Fr, and most preferably about 3 Fr insize so that it is small and flexible enough to shrink select portionsof the aneurysm as shown by dotted lines 181 in FIG. 39. The catheter180 may, of course, be sized larger to shrink larger portions of theaneurysm or other tissue structures. The catheter 180 has a tip 182which is made of a heat-resistant, non-stick material (such as PTFE) sothat the tip can contact the tissue during heating without sticking tothe tissue. The catheter 180 may also be a hypotube, guidewire orsimilar device without departing from the scope of the invention. Thetip 182 forms a chamber 183 and has holes 186 formed therein fordelivery of a conductive fluid as described below.

[0099] The catheter 180 has a lumen 184 which communicates with thechamber 183 in the tip 182. The lumen 184 is coupled to the source offluid 18 (see FIG. 1) which is preferably hypertonic saline. An RF probe188 passes through the lumen 184 and is coupled to the energy supply 12(see FIG. 1) which is preferably an RF generator. The RF probe 188 hasan electrode 189 positioned in the chamber while a second electrode (notshown) is positioned in contact with the patient's skin in theconventional manner. When the conductive fluid is delivered through thelumen 184, electrical energy is conducted by the conductive fluid toheat the aneurysm. The holes 183 in the tip 182 may be distributedaround the tip 182 (FIGS. 39 and 41), positioned at the distal end 185(FIG. 42) or along the sides 187 (FIG. 43) of the tip 182.

[0100] After the volume of the aneurysm has been reduced, the aneurysmmay be treated in any other manner described herein. Furthermore, thecatheter 180 of FIGS. 39-43 may be used to heat tissue or fluid inconnection with any of the other embodiments described herein and inparticular as a substitute for the device 84 of FIGS. 16 and 17.Finally, the catheter 180 may be used to heat tissue for any othersuitable purpose including those described above. For example, thecatheter 180 may be useful in treating venous insufficiency, deep veinreflux or for vein stripping. Furthermore, the catheter 180 may beuseful for treating urinary incontinence.

[0101] While the above is a description of the preferred embodiments ofthe invention, various alternatives, modifications, and equivalents maybe used. For example, the expandable device may take any other shape andthe sealant may be any other suitable sealant. Furthermore, thedimensions and characteristics of any of the expandable members may beincorporated into any of the other expandable devices described hereinwithout departing from the scope of the invention. Finally, theexpandable devices are preferably used when shrinking the aneurysm butthe expandable devices may have various features which may be usefulwhen simply filling the aneurysm in the conventional manner.

What is claimed is:
 1. A method of treating a cerebral aneurysm,comprising the steps of: providing an expandable structure movable froma collapsed shape to an expanded shape; introducing the expandablestructure into a blood vessel of a patient; advancing the expandablestructure through the patient's vasculature to a cerebral aneurysm whilethe expandable structure is in the collapsed position; moving theexpandable structure into the cerebral aneurysm; expanding theexpandable structure to the expanded position in the cerebral aneurysm;shrinking the wall of the aneurysm; and leaving the expandable structurein the aneurysm after the shrinking step.
 2. The method of claim 1,wherein the shrinking step is carried out until the aneurysmal wallcontacts the expandable structure.
 3. The method of claim 1, wherein theshrinking step is carried out by delivering electrical energy to theexpandable structure to generate heat which shrinks the aneurysm wall.4. The method of claim 3, further comprising the step of: deliveringsaline to the aneurysm while delivering the electrical energy.
 5. Themethod of claim 3, wherein the shrinking step is carried out for atleast 5 seconds.
 6. The method of claim 1, wherein the shrinking step iscarried out by providing a heated fluid in the aneurysm to heat theaneurysmal wall.
 7. The method of claim 1, wherein the introducing stepis carried out with the expandable structure having a permeable portionwhen in the expanded position.
 8. The method of claim 7, wherein theshrinking step is carried out by delivering RF energy to the aneurysmwherein heated fluid in the aneurysm leaks through the permeable portionand into the parental vessel.
 9. The method of claim 1, wherein theintroducing step is carried out with the expandable structure beingadvanced through the patient's vasculature with a catheter, the catheterhaving a lumen.
 10. The method of claim 1, further comprising the stepsof: coupling the lumen to a source of fluid; and infusing the fluid intothe aneurysm through the lumen.
 11. The method of claim 10, wherein theinfusing step is carried out so that the fluid seals the aneurysm toisolate the aneurysm from the parental vessel.
 12. The method of claim1, wherein the shrinking step is carried out so that the aneurysmal wallcontacts the expandable structure and reduces the size of the expandablestructure after the expanding step.
 13. A method of isolating a cerebralaneurysm from the parental vessel, comprising the steps of: providing adevice movable from a collapsed position to an expanded position, thedevice having a proximal portion when in the expanded position;introducing the device into the aneurysm in the collapsed position;expanding the device to the expanded position after the introducingstep; shrinking the dome of the aneurysm so that that the proximalportion of the expandable device extends around the neck of theaneurysm.
 14. The method of claim 13, wherein the providing step iscarried out with the proximal portion being permeable, the proximalportion being configured to form a thrombus to isolate the aneurysm fromthe parental vessel.
 15. The method of claim 14, wherein the providingstep is carried out with the proximal portion forming a permeablebarrier having an opening size of no more than 1 mm when viewed in adirection perpendicular to blood flow through the parental vessel.
 16. Asystem for treating a cerebral aneurysm, comprising: a shaft having alength and flexibility sufficient to extend into a patient's cerebralvasculature; an expandable device movable from a collapsed shape to anexpanded shape, the expandable device being removably coupled to theshaft; means for shrinking the aneurysmal wall toward the expandabledevice when the expandable device is contained within the aneurysm. 17.The system of claim 16, wherein the shrinking means includes anelectrical power supply coupled to the expandable device.
 18. The systemof claim 17, wherein the electrical power supply is an RF generator. 19.The system of claim 18, wherein the expandable device acts as anelectrode and is electrically coupled to the RF generator.
 20. Thesystem of claim 16, wherein the shaft has a lumen passing therethrough.21. The system of claim 20, further comprising: a source of conductivefluid coupled to the lumen.
 22. The system of claim 16, wherein theshrinking means is a device selected from the group consisting of RF,resistance heating, laser and chemical action.
 23. The device of claim16, wherein the shrinking means heats the fluid passing through thelumen so that the heated fluid shrinks the aneurysm.
 24. A method oftreating a cerebral aneurysm, comprising the steps of: providing anexpandable structure movable from a collapsed shape to an expandedshape, the expandable structure having a deforming portion which isdisplaced beyond the yield strength when moving from the collapsedposition to the expanded position; introducing the expandable structureinto a blood vessel of a patient; advancing the expandable structurethrough the patient's vasculature to a cerebral aneurysm while theexpandable structure is in the collapsed position; moving the expandablestructure into the cerebral aneurysm; expanding the expandable structureto the expanded position in the cerebral aneurysm; and leaving theexpandable structure in the aneurysm after the expanding step.
 25. Themethod of claim 24, wherein the providing step is carried out with theexpandable structure occupying a volume of at least 50-70%.
 26. Themethod of claim 24, wherein the providing step is carried out with theexpandable structure having a maximum opening size of no more than 15 mmwhen in the expanded position.
 27. The method of claim 24, wherein theproviding step is carried out with the expandable structure having firstand second ends, the deforming portion extending between the first andsecond ends; and the expanding step is carried out with the first andsecond ends moving toward one another so that the deforming portionplastically deforms.
 28. The method of claim 27, wherein the providingstep is carried out with the deforming portion including at least threeposts extending between the first and second ends.
 29. The method ofclaim 24, wherein the providing step is carried out with the deformingportion holding a number of flexible filaments in the expanded position,the flexible filaments being deformed elastically when in the expandedposition.
 30. A device for introduction into a cerebral aneurysm,comprising: a first end having a first hub; a second end having a secondhub; and an expandable structure extending between the first and secondends, the expandable structure being movable from a collapsed shape toan expanded shape, the expandable structure having at least twofilaments extending between the first and second hubs, the first andsecond hubs moving toward one another when the expandable structuremoves from the collapsed position to the expanded position.
 31. Thedevice of claim 30, further comprising: a locking mechanism which locksthe expandable structure in the expanded position.
 32. The device ofclaim 30, further comprising: a fluid flow path extending through theexpandable structure for introduction of a fluid into the aneurysm. 33.The device of claim 30, wherein the expandable structure is naturallybiased toward the collapsed condition.
 34. A method of treating ananeurysm in the cerebral vasculature of a patient, comprising the stepsof: providing a device having first and second ends and an expandablestructure extending between the first and second ends, the expandablestructure being movable from a collapsed shape to an expanded shape, thedevice also having a locking mechanism for locking the expandablestructure in the expanded position; introducing the device into thepatient's vascular system with the expandable structure in the collapsedposition; advancing the device through the patient's vascular systemwith the expandable structure in the collapsed condition; positioningthe device into an aneurysm in the patient's cerebral vasculature;expanding the expandable structure of the device after the positioningstep; and locking the locking mechanism to hold the expandable structurein the expanded position.
 35. The device of claim 34, wherein theproviding step is carried out with the expandable structure beingnaturally biased toward the collapsed position when in the expandedposition.
 36. The device of claim 34, wherein the providing step iscarried out with the expandable structure having a mesh structure. 37.The device of claim 34, wherein the providing step is carried out withthe expandable structure having a number of elongate members extendingbetween the first and second ends.
 38. The device of claim 34, furthercomprising the step of: heating the aneurysm to shrink the aneurysm. 39.The device of claim 34, wherein the heating step is carried out with aheated fluid.
 40. The device of claim 34, wherein the heating step iscarried out by delivering electrical energy to the expandable portion.41. The device of claim 34, wherein the providing step is carried outwith the expandable structure being substantially cylindrical in thecollapsed position, the expandable structure having a longitudinal axis;the expanding step being carried out with the expandable structuremoving radially outward relative to the longitudinal axis.
 42. Thedevice of claim 34, wherein the first and second ends move towards oneanother by a distance of 10-15 mm, the expandable structure having adiameter, the diameter increasing at a portion of the expandablestructure between 0.020 and 0.600 inch when moving from the collapsedposition to the expanded.
 43. A method of treating a cerebral aneurysm,comprising the steps of: providing a catheter having a cover; passingthe catheter through a patient's cerebral vasculature to an aneurysm;positioning the cover over the neck of the aneurysm; and shrinking theaneurysmal wall.
 44. The method of claim 43, wherein the shrinking stepis carried out by heating the aneurysmal wall.
 45. The method of claim43, wherein the providing step is carried out with the catheterincluding a lumen having an outlet.
 46. The method of claim 45, furthercomprising: introducing a fluid into the aneurysm through the lumen. 47.The method of claim 43, further comprising the step of: introducing anelectrode in the aneurysm; and the shrinking step being carried out bydelivering electrical energy to the electrode to heat the aneurysmalwall.
 48. The method of claim 47, wherein the electrode introducing stepis carried out with the electrode being on a guidewire passing through alumen in the catheter.
 49. The method of claim 48, further comprisingthe step of: introducing a second electrode into the patient.
 50. Themethod of claim 49, wherein the second electrode is introduced on theguidewire.
 51. The method of claim 49, wherein the second electrode isintroduced on the catheter.
 52. The method of claim 43, wherein thecovering step is carried out with the cover being permeable.
 53. Themethod of claim 43, further comprising the step of: delivering asubstance into the aneurysm after the shrinking step, the substanceremaining in the aneurysm to seal the aneurysm.
 54. The method of claim53, wherein the delivering step is carried out with the substance beingselected from the group consisting of cyanoacrylates, ethylenevinyl-alcohol, cellulose acetate polymers, and fibrin glues.
 55. Themethod of claim 43, wherein the cover is composed of silicone.
 56. Amethod of treating an aneurysm, comprising the steps of: providing anexpandable device movable from a collapsed position to an expandedposition, the expandable device having a first section and a secondsection; passing the expandable device through a patient's cerebralvasculature; introducing the expandable device into an aneurysm in thepatient's cerebral vasculature; expanding the expandable device to theexpanded position with the first section positioned adjacent to the neckof the aneurysm and the second section positioned further into theaneurysm; coupling the expandable device to a source of electric power;delivering the electric power to the expandable device so that theaneurysm is heated thereby shrinking the aneurysm, the heat beinggenerated by the second section and not the first section so that theneck of the aneurysm is protected.
 57. The method of claim 56, whereinthe providing step is carried out with the expandable device beingpermeable when in the expanded position.
 58. The method of claim 56,wherein the coupling step is carried out with the source of electricpower being an RF generator.
 59. The method of claim 56, wherein thedelivering step is carried out with the electric power being monopolarRF with the second section acting as the electrode.
 60. The method ofclaim 56, wherein the delivering step is carried out so that theaneurysm shrinks and contacts the expandable device so that theexpandable device is reduced in size from the expanded position.
 61. Amethod for treating an aneurysm and a parent vessel, comprising thesteps of: providing a catheter and a coil, the catheter having a lumenand the coil being positioned in the lumen, the coil being movablewithin the lumen to extend and retract the coil from the distal end ofthe catheter; introducing the catheter into a patient's vascular system;advancing the catheter to an aneurysm; filling the aneurysm with aheated fluid; positioning the coil in the parent artery so that windingsare positioned adjacent the neck of the aneurysm to impede flow betweenthe aneurysm and the parent artery.
 62. The method of claim 61, whereinthe filling step is carried out by introducing a catheter into theaneurysm through the windings in the coil, the catheter having means forheating fluid.
 63. The method of claim 62, wherein the filling step iscarried out with the heating means being an RF electrode.
 64. The methodof claim 61, wherein the providing step is carried out with the coil afirst deployed position and a second deployed position, the seconddeployed position having more coil extended from the distal end of thecatheter and having greater pitch than when the coil is in the firstdeployed position.
 65. The method of claim 61, wherein the providingstep is carried out with the coil being made of a shape memory alloy.66. A device for regulating fluid flow between an aneurysm and a parentvessel, comprising: a catheter including a lumen having a distal end;and a coil positioned within the lumen, the coil being movable withinthe lumen to extend or retract the coil from the distal end of thelumen, the coil being extending from the lumen to form a coil.
 67. Thedevice of claim 66, wherein the coil is movable from a first deployedposition to a second deployed position, the exposed portion of the coilextending from the catheter having a greater pitch in the seconddeployed position than in the first deployed position and being extendedfurther from the distal end of the catheter.
 68. The device of claim 67,wherein the coil forms windings having a diameter of 1 mm to 3 mm.
 69. Adevice for heating tissue, comprising: a shaft having a lumen; a tiphaving a chamber therein and a plurality of holes leading to thechamber, the chamber being fluidly coupled to the lumen so that a fluiddelivered through the lumen passes into the chamber and out theplurality of holes; and an RF electrode configured to deliver RF energyfrom an RF generator, the RF electrode positioned in the chamber. 70.The device of claim 69, further comprising: a source of conductive fluidcoupled to the lumen.
 71. The device of claim 69, wherein the shaft hasa size of no more than 5 French.
 72. The device of claim 69, wherein theplurality of holes in the tip are positioned along sides of the tip. 73.The device of claim 69, wherein the plurality of holes in the tip arepositioned at a distal end of the tip.